Interestingly, and I just confirmed this with an official source, the order does NOT apply to USMC personnel, or (at this time) US Army or Air Force personnel. Since the USS Reagan battle group is already at sea, that means only a few hundred shore duty people are actually impacted.
The official I spoke to said the Marines at Yokosuka and at the Embassy will be expected to comply voluntarily, but did not comment about the Marines on Okinawa.
Maybe the Coasties that are there this week will get some good liberty!